1. Field of the Invention
This invention relates to a resistor layer for a field emission device and the like, and more particularly, to a resistor layer that prevents shorting in a field emission display baseplate.
2. Description of the Related Art
A field emission device (FED) typically includes an electron emission tip configured for emitting a flux of electrons upon application of an electric field to the field emission device. An array of miniaturized field emission devices can be arranged on a plate and used for forming a visual display on a display panel. Indeed, field emission devices have been shown to be a promising alternative to cathode ray tube display devices. For example, field emission devices may be used in making flat panel display devices for providing visual display for computers, telecommunication and other graphics applications. Flat panel display devices typically have a greatly reduced thickness compared to the generally bulky cathode ray tubes.
Field emission display devices are currently being touted as the flat panel display type poised to take over the liquid crystal display (LCD) market. FEDs have the advantages of being lower in cost, with lower power consumption, having a better viewing angle, having higher brightness, having less smearing of fast moving video images, and being tolerant to greater temperature ranges than other display types.
One problem with FEDs has been the shorting of the resistor layer. In the FED structure, a resistor layer is typically provided over a metallic layer in an FED baseplate. Conventional materials used are a boron-doped amorphous silicon for the resistor layer, and chromium, aluminum, aluminum alloys or a combination of such materials for the metallic layer. Short-circuiting of the device may occur in this structure because of diffusion of silicon from the resistor layer into the metal at temperatures above about 300° C. This problem is especially prevalent when the resistor layer is deposited directly over an aluminum layer. Diffusion of silicon into the aluminum will take place, for instance, during deposition at temperatures from about 330 to 400° C., or during packaging of the baseplate at temperatures of about 450° C. This diffusion problem is caused primarily because Si forms a eutectic contact with Al above 400° C., and also because the free energy of silicon is higher in its amorphous state.
Another problem is that resistor layers made of boron-doped amorphous silicon cause nucleation related defects at the interface of the resistor and metal, especially when the metal is chromium. In an FED structure using a chromium metallic layer, for instance, the interaction of diborane gas at the chromium surface causes irregularities at the surface between the metal and resistor. Discontinuities in the resistor layer can cause the loss of the benefits for which the resistor layer was used in the first place. Additionally, discontinuities in the resistor layer can present problems when subsequent etching or photolithographic processes are conducted, potentially causing delamination of various layers and other irregularities.
Accordingly, what is needed is an improved resistor having fewer defects and discontinuities to prevent short-circuiting in FED devices and the like.